I've broken a crap load of bones in my 18 years of living (lost count, guessing 15ish) and I actually kept one as a memento because it was glow in the dark and I was 8. They have to split it with a saw to take it off, but we tore out most of the soft lining and it sat in my cupboard for years. So they probably could

In all honesty, no idea. I'm not a very sporty person (mainly for this reason) so they've all been relatively low impact, but more severe than they should be. Trip over my own feet? Boom, your left wrist will never be the same again. Up until a few months ago, I thought I had a very mild form of Osteogenesis Imperfecta (OI), and I was diagnosed with it based on my symptoms. But other medical issues in my family led to us all having genetic testing done, and I found out I don't have the gene mutation that causes OI. It's probably something new/unique to me, my family has some interesting genetic quirks.

Broken arms guy didn't actually break his arms. He lost the use of his arms and then reddit joked that he must've broken them. He let everyone believe it because it increases his cover and makes him harder to locate.

You can verify all of this by reading over /u/verifiedson 's comments.